1. Field of the Invention
The invention relates to a seal for sealing a constant velocity joint as well as a correspondingly sealed cardan shaft.
2. The Prior Art
There are several applications for cardan shafts and/or constant velocity joints in the sector of technical mechanical engineering. Force-transferring constant velocity joints are used in the automotive industry, in which the cardan shaft is used between the power take-off of the transmission and the drive train.
A cardan shaft according to the state of the art is generally composed of an outer ring that accommodates the joint mechanism, which ring is configured as a corpus element that accommodates the joint, and at least one lid that closes off the outer ring with regard to the surroundings. Passages for corresponding connection shafts are provided in the region of the lid. The inner region of the outer ring, particularly the region of the joint, is filled with a lubricant for operation, and grease is preferably pressed into it, in order to minimize the wear due to friction. So that the lubricant applied into the inner region of the cardan shaft does not exit to the outside, it is necessary to seal the lid that closes off the outer ring, accordingly.
From the state of the art, for example from German Patent Application No. DE 198 57 460 A1, seal arrangements for a constant velocity joint are known, in which sealing means are introduced between the contact surfaces of the outer ring and the lid, which lie opposite one another. These sealing means are squeezed between the contact surface of the lid and the contact surface of the outer ring when attachment screws are tightened, and thus make the desired sealed condition available.
In ongoing operation, particularly during transfer of engine forces, the housing of the cardan shaft occasionally experiences greater torque surges, which can individually lead to a slip of up to 0.3 mm of the housing lid relative to the outer ring. In addition, cardan shafts, particularly when used in the motor vehicle sector, can be exposed to significant variations in operating temperature, so that in winter, for example, a cold-started car can have temperatures far below 0° C., but the operating temperature of a cardan shaft increases to 120° C. to 150° C. in ongoing operation.
Because of the torque surges and the thermal material expansion, particularly when using different materials, there is always the problem, in conventional seals, that they can slip, and project into the inner region of the outer ring, in other words into the joint mechanism, for example. As the result of such a problem, a leak occurs, for one thing, which leads to a constant loss of the lubricant medium—in the long term, the joint fails as a result.